I am currently exploring the hypothesis that the combination of oxalates and calcium in meals or on the same day makes me particularly sick, possibly exacerbated by certain types of fat, fructose, carotinoids, acids or some fibers.
Perhaps the worst food of all is spinach lasagna, which has lots of oxalates and carotinoids in the spinach and whole grains, lots of fat of all sorts, fiber in the whole grains and even some fructose in the onions/garlic.
When I eat plain lentils, that's usually ok up to a certain point. But when I add higher quantities of kale (high in calcium), it appears to become a problem.
I do not really think it's the oxalate per se, because calcium should BLOCK oxalate absorption. Especially the high load of calcium in the copious amounts of cheese used in the spinach lasagna.
I think it's a bacterial fermentation product made from oxalates.
Whatever it is, I seem to be tolerating white pasta much better than whole grain, so I switched to that. And I probably won't combine kale with legumes anymore, which have higher amounts of oxalates.
That all being said, I am not entirely sure this is about oxalates. Could be some fiber, phytate, tannin, saponin or other compound present in whole grains and legumes. I think it's oxalates because spinach makes everything so much worse.
Apart from that, it has been confirmed again that plant-based Omega-3s must be avoided (tried a vegan margarine with 3% omega 3 from walnut oil...not good).
On the brighter side, it looks like some restrictions regarding oils and fats can be relaxed if the meals do not contain high oxalate or high fiber foods, i.e., white bread with low-oxalate nut butters (e.g., hazelnut) could be introduced occasionally.